Protests against the Dakota Access pipeline are gaining more traction as more celebrities join in.

Previously, other celebrities known for their political activism, such as Susan Sarandon and Shailene Woodley, had appeared with members of the Standing Rock Sioux tribe outside of a Washington DC courthouse to protest against the pipeline. The pipeline, which is a project of the firm Energy Transfer Partners, is a $3.8-billion project that, according to the Sioux, will endanger tribal lands and resources. The Dakota Access pipeline is planned to transport up to 570,000 barrels of crude oil a day from North Dakota to Illinois. The currently planned route of the pipeline places it less than a mile away from the Standing Rock reservation and it would also cross the Missouri river, meaning that a leak in the pipeline could endanger the entire region.

Leonardo DiCaprio, who has previously spoken out about climate change and corporate greed, took to twitter to show his support saying he “stands with the Great Sioux Nation to protect their water and lands.” DiCaprio also shared a link to a Change.Org petition to stop the Dakota Access pipeline. The petition was written by a 13-year-old Standing Rock Sioux member, Anna Lee Rain Yellowhammer, and is only a few thousand signatures short of its 300,000 goal. DiCaprio’s tweet also used the #KeepItInTheGround hashtag, which calls to end the extraction of fossil fuels.

DiCaprio’s expression in support of the protestors occurred alongside other messages of protest against the pipeline from several actors in the new Justice League movie. Jason Momoa has posted various photos on Instagram in a show of solidarity while Ezra Miller and Ray Fischer appeared in a joint video to express their opposition to the pipeline. In the video, Ezra Miller says “We want to say that our hearts are with the Native youth of the Standing Rock Reservation, and that we oppose the Dakota Access Pipeline” while Fischer urged others to visit Rezpect our Water, a website set up by Standing Rock youth to stop the pipeline. Miller, Fischer, and Momoa also appeared in a joint video on Instagram along with other Justice League actors Ben Affleck and Gal Gadot to help spread awareness about the pipeline protest.

These more recent celebrity endorsements followed confrontations between protestors and a private mercenary group hired by Dakota Access. The mercenary group, G4S, used dogs that bit several protestors, including women and children. Dakota Access also stands accused of intentionally destroying Sioux burial grounds on purpose before a court could confirm the historical and cultural value of the area. Both incidents caused outrage in social media over the past week. Celebrity interest in the issue has only added to the protest’s momentum as the controversial pipeline is becoming a key issue. Fortunately, yesterday, in a stunning decision, the US Dept of Justice temporarily halted the construction of the pipeline. Could the influence of celebrities on public opinion have affected the government’s decision?